System and method of delivering local anesthesia

ABSTRACT

A catheter and introducer needle assembly is provided including a catheter adapter at its proximal end. The catheter adapter includes a side port in fluid communication with the catheter and a septum located in the proximal end of the catheter adapter proximal of the side port. The introducer needle is connected at its proximal end to a needle hub and includes at least one notch in communication with the introducer needle lumen. The notch allows blood to flow into the open distal end of the needle and through the notch into the catheter lumen (specifically, the annular space between the outside of the introducer needle and the inside of the catheter and catheter adapter). Thereafter, the blood can flow through the annular space and then through the side port and extension tube that extends from the catheter adapter.

RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No. 10/682,848filed Oct. 10, 2003, which claims benefit under 35 U.S.C. § 119(e) fromU.S. Provisional Patent Application No. 60/417,728, filed on Oct. 10,2002, the entire content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to systems and methods of delivering anesthesiato tissue. Specifically, the invention relates to systems and methods ofproviding anesthesia to tissue using a catheter and introducer needleassembly, and applying a current to the needle assembly to createstimulation in the tissue to identify a target needle depth at which todeliver the anesthesia. The present application

2. Description of the Related Art

In certain instances, it is desirable to provide anesthesia at a pointin a patient's tissue proximate to a nerve. Such procedures are known asperipheral block procedures. Typically, the clinician employs a hollowneedle that is coated with an electrical insulator, leaving only the tipof the needle exposed. The clinician first locates anatomical landmarksto establish the location of the nerve. As the needle is inserted intothe tissue, a small electric current is passed through the needle. Thecurrent passes to the patient's tissue at the tip of the needle (theonly exposed portion of the needle) and causes surrounding muscle tissueto contract or “twitch.” This twitching is observed by the clinician andhelps locate the needle tip. As the needle tip proceeds closer to thenerve, the clinician reduces the current and moves the needle tip to apoint that is believed to be appropriately close to the nerve to beeffective.

Once the needle tip is in place, the clinician delivers a bolus ofanesthesia through the needle to the region around the nerve. Typically,such a delivery of anesthesia will deaden both the motor and sensoryimpulses. After delivery of the anesthesia, the rigid needle iswithdrawn. Consequently, if more anesthesia is required, another needlemust be inserted. Alternatively, some practitioners will insert acatheter through the needle so that the tip of the catheter is near thetip of the needle. The needle is then withdrawn over the catheter andthe catheter remains in place. After the needle is threaded off thecatheter, a special connector is attached to the catheter end to permitthat delivery of additional anesthesia. This can be a time consumingprocess.

SUMMARY OF THE INVENTION

It is an aspect of one implementation of the invention to provide asystem and method for delivering anesthesia via a needle while providinga catheter for delivery of additional anesthesia over time.

It is an aspect of another implementation of the invention to provide adevice and method adapted for delivering anesthesia to tissue via both aneedle and a catheter, at the election of the clinician.

It is an aspect of yet another implementation of the invention toprovide a system and method for locating the tip of the needle withinthe patient's tissue before delivering anesthesia or withdrawing theneedle.

In accordance with one implementation of the invention, a catheter andintroducer needle assembly is provided including a catheter adapter atits proximal end, which preferably includes at least one wing radiallyextending from the catheter adapter. The catheter adapter also includesa side port in fluid communication with the catheter. A septum islocated in the proximal end of the catheter adapter proximal of the sideport. Preferably, the septum prevents any fluid from flowing into or outof the proximal end of the catheter adapter and thus diverts any fluidflowing in the catheter lumen into the side port. Similarly, the septumdiverts any fluid flowing from the side port into the catheter lumen.The septum has a hollow interior portion to minimize drag on theintroducer needle as it is being withdrawn from the catheter through theseptum.

The introducer needle is connected at its proximal end to a needle huband preferably includes at least one notch, i.e., a hole or opening inthe sidewall, formed therein in communication with the introducer needlelumen (or “central bore”). The notch is formed in the introducer needlesuch that fluid can flow between the central bore of the needle and thecatheter adapter. When delivering anesthesia through the needle,anesthesia fluid is delivered through the extension tube to the sideport. From the side port, the fluid enters the catheter adapter andproceeds either directly through the notch, or travels in the annularspace between the needle and the catheter, and then through the notch(depending on the position of the notch along the needle). Passingthrough the notch, the fluid passes through the central bore and out ofthe tip of the needle. As shown, the notch may be positioned near thetip of the needle within the catheter. The notch can also be positionedelsewhere and still practice aspects of the invention. For example, thenotch may be positioned on the needle within the catheter adapteraligned with the side port, as discussed in U.S. Pat. No. 5,935,110,incorporated herein by reference, to encourage flow through the needle.

It will be appreciated that this structure permits the flow of liquidthrough the side port to either the annular space between the needle andthe catheter (or a notch that may positioned on the needle within thecatheter adapter), through the notch into the lumen within the needle,and out of the tip of the needle. When the needle is removed, thecatheter adapter remains in place, permitting later delivery of fluidsthrough the catheter. Access to the side port may be through a closedsystem access port, thereby ensuring that an open conduit to theenvironment is not created.

In accord with certain implementations of the invention, an electricalconnection may be provided to the needle via the needle hub. Ahand-held, battery powered device may be connected to the electricalconnection, thereby providing an appropriate charge. The needle may bemade of an electrically conductive material, such as stainless steel.The catheter, however, is made of a material that acts as an electricalinsulator. Therefore, only the tip of the needle carries the electricalcharge to the patient's tissue. As the clinician inserts the catheterassembly into the patient's tissue, an electrical charge may bedelivered through the needle to the tissue. Certain tissue will respondto the electrical charge by twitching. Specifically, muscles willcontract under an electrical charge. Consequently, the clinician can usethis information, along with other indicia, to determine the location ofthe tip of the needle during insertion. After the clinician confirmsproper placement of the catheter assembly into the patient's tissue, theclinician delivers liquid anesthesia to that tissue by supplying theanesthesia to the side port of the catheter assembly. Preferably, theclinician delivers the anesthesia using a syringe attached to theextension tube. The clinician then withdraws the introducer needle fromthe catheter by pulling the needle hub in a proximal direction. Theseptum should be long enough so that both the notch and the open distalend of the introducer needle can be located simultaneously within theseptum, such as described in U.S. Pat. No. 6,506,181, incorporatedherein by reference. This ensures no blood or anesthesia leakage occurswhen the introducer needle is being withdrawn from the catheter. If theseptum is too short, the open distal end of the introducer needle couldbe distal of the distal end of the septum in the fluid flow path whilethe notch could be located proximal of the proximal end of the septum.This could allow fluid to leak from the catheter when the introducerneedle is being withdrawn.

During infusion of the anesthetic, it is desirable that a clinician beable to aspirate though the device to assure that the needle point isnot accidentally located within an artery (which anatomically is verynear the target nerves). The need to aspirate is so that a clinician candetermine if the device is in the venous system prior to infusingsignificant amounts of anesthetic, which could result in a verydetrimental result if infused into the venous system. If the deviceaccidentally penetrates an artery, during aspiration blood would bedrawn through the needle point, out through the notch in the needle, andvisualized in the annular space between the needle and the catheter andall fluid connection locations proximal of the notch (i.e. catheteradapter and extension tubing) if the notch is located near the distalend of the needle. If the notch is located in the catheter adapter theaspirated blood would be visualized in the clear/translucent catheteradapter and points proximal of the notch located within the catheteradapter.

Once the needle is withdrawn, the catheter remains in place, with thetip of the catheter disposed in the tissue being anesthetized. Overtime, the clinician may determine that additional anesthesia needs to beapplied. In such case, the clinician operably connects a source ofanesthesia to the fluid access device on the extension tube. The fluidanesthesia passes through the extension tube, into the catheter adapterand into the catheter itself. The fluid anesthesia then passes throughthe catheter lumen into the patient's tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an integrated catheter and introducerneedle for use in accordance with an aspect of this invention;

FIG. 2 is an exploded perspective view of an integrated catheterassembly of FIG. 1;

FIG. 3 is a perspective cross-sectional view taken along line 3-3 inFIG. 1 showing the catheter and introducer needle assembly having afirst embodiment of the low drag septum, with a portion of theintroducer needle assembly in phantom, prior to insertion into apatient;

FIG. 4 is a perspective cross-sectional view similar to the view of FIG.3 after the catheter assembly has been inserted into a patient butbefore the introducer needle has been completely retracted from thecatheter assembly with the distal portion of the introducer needledisposed in the distal portion of the septum;

FIG. 5 is a perspective cross-sectional view similar to the view of FIG.3 after the catheter assembly has been inserted into a patient butbefore the introducer needle has been completely retracted from thecatheter assembly with the distal portion of the introducer needledisposed in the proximal portion of the septum;

FIG. 6 is a perspective cross-sectional view similar to the view of FIG.3 after the catheter assembly has been inserted into a patient with theintroducer needle completely retracted from the catheter;

FIG. 7 is a cross-sectional view of a portion of the integrated cathetertaken along line 7-7 in FIG. 1 without the introducer needle assembly;

FIG. 8 is a perspective cross-sectional view of the catheter andintroducer needle assembly similar to FIG. 3 but showing a differentrelationship between the introducer needle and the low drag septum wherethe distal tip of the introducer needle is distal of the distal end ofthe septum;

FIG. 9 is a perspective cross-sectional view of the catheter andintroducer needle assembly similar to FIG. 4 but showing a differentrelationship between the introducer needle and the low drag septum wherethe distal tip of the introducer needle is disposed in the distalportion of the septum;

FIG. 10 is a perspective cross-sectional view of the catheter andintroducer needle assembly similar to FIG. 5 but showing a differentrelationship between the introducer needle and the low drag septum wherethe distal tip of the introducer needle is disposed in the proximalportion of the septum;

FIG. 11 is a cross-sectional view similar to the view in FIG. 7 of aportion of the integrated catheter having the low drag septum butshowing the configuration of the second embodiment of the low dragseptum disposed in the catheter;

FIG. 12 is a schematic cross sectional view showing the catheterassembly inserted into a patient's tissue;

FIGS. 13A and 13B are top and side isolation views in partial cutawayshowing 25 the needle tip and catheter tip;

FIG. 14 is a perspective view of an integrated catheter and introducerneedle for use in accordance with another aspect of this invention;

FIG. 15 is an exploded perspective view of an integrated catheterassembly of FIG. 14;

FIG. 16 is a detailed perspective view of the catheter adapter of thecatheter as shown in FIG. 14;

FIG. 17 is a cross-sectional view taken along line 17-17 in FIG. 14showing the catheter and introducer needle assembly;

FIG. 18 is a detailed cross-sectional view of the catheter adapter shownin FIG. 16;

FIG. 19 is a cross-sectional view of an example of a luer lock adapterand luer lock about to engage the luer lock adapter;

FIG. 20 is a cross-sectional view of the luer lock engaged with the luerlock adapter shown in FIG. 19;

FIG. 21 is a perspective view of the luer lock adapter shown in FIG. 19;

FIG. 22 is a top view of the luer lock adapter shown in FIG. 19; and

FIG. 23 is a perspective view of an example of the relationship betweenthe needle assembly shown in FIG. 1 and the needle shield assembly whenthe needle shield assembly is extended over the needle tip.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used herein, the term “proximal” refers to a location with respect tothe device that, during normal use, is closest to the clinician usingthe device and farthest from the patient in connection with whom thedevice is used. Conversely, the term “distal” refers to a location withrespect to the device that, during normal use, is farthest from theclinician using the device and closest to the patient in connection withwhom the device is used.

As used herein, the term “top”, “up” or “upwardly” refers to a locationwith respect to the device that, during normal use, is radially awayfrom the longitudinal axis of the device and away from the patient'sskin. Conversely, as used herein, the term “bottom”, “down” or“downwardly” refers to a location with respect to the device that,during normal use, is radially away from the longitudinal axis of thedevice and toward the patient's skin,

As used herein, the term “in” or “inwardly” refers to a location withrespect to the device that, during normal use, is toward the inside ofthe device. Conversely, as used herein, the term “out” or “outwardly”refers to a location with respect to the device that, during normal use,is toward the outside of the device.

An integrated catheter and introducer needle assembly is shown generallyat 10 in FIG. 1. The catheter and introducer assembly may be configuredas described in U.S. patent application Ser. No. 09/865,918,incorporated herein by reference. Of course, other assemblies may beused and practice aspects of the invention, such as the assemblydescribed in U.S. patent application Ser. No. 09/717,148, incorporatedherein by reference. Specifically, the catheter and introducer assemblymay include a shield 200 or other device designed to capture the tip ofthe needle as it is withdrawn from the assembly, as disclosed in U.S.patent application Ser. No. 09/717,148, incorporated herein byreference. Further details of a catheter and introducer assembly can bealso found in U.S. patent application Ser. No. 09/590,600 and in WO01/93940, the entire contents of both of these documents beingincorporated herein by reference.

As shown, the catheter assembly 20 includes catheter 21 affixed tocatheter adapter 24. Suitable materials for catheter 21 include, but arenot limited to, thermoplastic resins such as fluorinated ethylenepropylene (FEP), polytetrafluoroethylene (PTFE), polyurethane and thelike. The catheter 21 is formed from a thermoplastic hydrophilicpolyurethane that softens with exposure to physiological conditionspresent in the patient's body. Importantly, the catheter is preferablymade of a material that does not occlude during use and that acts as anelectric insulator. The electric insulation characteristic of thecatheter material should be such that the electric charge passingthrough the needle, discussed below, does not pass through the catheterto the patient's tissue. In addition, the material used to form catheter21 may be transparent or at least translucent to reduce visualinterference with the clinician. The catheter material should also beselected so that it does not interact with the intended liquidanesthesia. Suitable materials for catheter adapter 24 include, but arenot limited to, thermoplastic polymeric resins such as polycarbonate,polystyrene, polypropylene and the like. The material used to formcatheter adapter 24 may be transparent or at least translucent to allowthe clinician to view the flow of anesthesia there through.

Catheter adapter 24 includes a side port 22, which has an extension tube25 connected thereto. Extension tube 25 is preferably formed from atranslucent material such as polyvinyl chloride, polyurethane and thelike to facilitate visualization of the anesthesia through extensiontube 25. The proximal end 127 of extension tube 25 may include aclosed-system access port, such as luer lock adaptor 126. The closedsystem-access port may include the needleless luer access connector asshown in FIGS. 19-22 and disclosed in U.S. Pat. No. 6,171,287,incorporated herein by reference, or other fluid access device to allowthe connection of an anesthesia or other IV fluid supply line toextension tube 25. Preferably, the closed system access port is designedto receive a luer lock, luer slip or other connector. The closed systemaccess port may also be a PRN adapter. In any event, it is desirablethat the port maintain a seal against the environment until accessed bya syringe tip or other device.

Specifically, as shown in FIGS. 19-22, the needleless luer accessconnector includes a housing 410 having a top portion 412 and bottomportion 416. Typically plastic materials such as polycarbonate, or PETGcould be used to form housing 410. Housing 410 defines an inlet 411 andan outlet 417 with a cavity or bore 413 extending therebetween. Inlet411 is defined at the top of top portion 412 and outlet 417 is definedat the bottom of bottom portion 416 of the needleless luer accessconnector. Inlet 411, and thus that portion of bore 413 adjacent toinlet 411 and that portion of top portion 412 adjacent to inlet 411,must be sized and configured in conformity with at least some of theInternational Standards Organization (ISO) standards for a female luerconnection. This will allow a male luer slip or lock to be connected toinlet 411. Thus, inlet 411 has a maximum external diameter of about0.265 inches (6.73 millimeters) and an internal diameter of about 0.214inches (5.44 millimeters) to allow a male luer taper to extend intoinlet 411. The exterior of the top of top portion 412 includes luerthreads 414 that allow another medical device having a male luer lock tobe connected to the top of proximal portion 412. Alternatively, no luerthreads 414 need be formed on the exterior of the top of top portion 412so that another medical device having a male luer slip can be connectedto the top of top portion 412. Outlet 417, and thus that portion of bore413 adjacent to outlet 417 is sized and configured as a male luer taperthat complies with the ISO standards for a male luer taper. ISO standard594-2:1986(E) requires that the male luer taper have a minimum length ofabout 0.2953 inches (7.5 millimeters). Forming this part of housing 410in accordance with ISO standards allows the needleless luer accessconnector of this invention to be connected to a standard female luerconfiguration of another medical device. If desired, a luer lock collar416 a may be formed about the male luer taper to lock the connector to afemale luer. In such a case, the luer lock should comply with ISOstandards. According to ISO standards, the root diameter R of the threadon the male luer lock fitting should be about 0.315 inches (8millimeters) and the crest diameter C of the thread on the male luerlock fitting should be about 0.276 inches (7 millimeters). In addition,the male luer taper must extend a minimum of about 0.083 inches (2.1millimeters) past the end of luer lock collar 416 a.

The top surface 415 of top portion 412 adjacent to inlet 411 transitionsbetween two high points and two low points. Each high point is about 180degrees apart from each other and each low point is also about 180degrees apart from each other such that each high point is about 90degrees from each low point. Preferably, each high point should begreater than zero but less than about 0.050 inches (1.143 millimeters)higher than each low point. Most preferably, each high point should beabout 0.027 inches (0.686 millimeters) higher than each low point. Toachieve a smooth circumferential top surface 415 that transitions in asmooth undulating fashion between high points and low points, topsurface 415 can be formed by using a curved surface with a radius ofabout 0.30 inches (7.62 millimeters) as the template to cut the top ofproximal portion 412. In geometric terms, an imaginary cylinder definedby the top of proximal portion 412 can be cut with an imaginary cylinderhaving a radius of about 0.30 inches (7.62 millimeters) oriented 90degrees to the longitudinal axis of the imaginary cylinder defined bythe top of proximal portion 412. This results in top surface 415 havingthe shape described. By changing the radius of the imaginary cylinder,the distance between high points and low points can be changed.

A septum 420 is located in top portion 412 of the needleless luer accessconnector to control fluid flow therethrough. Typically materials suchas silicone or polyisoprene could be used for form septum 420. Septum420 has an enlarged proximal portion 421, a medial portion 422 and anenlarged distal portion 423. The top of enlarged proximal portion 421can be formed with an annular lip 424 extending about the circumferenceof proximal portion 421. Lip 424 provides extra mass to give enlargedproximal portion 421 extra rigidity to prevent it from folding in whenit is accessed by a male luer taper. Lip 424 may also be bonded to theproximal portion of top portion 412. Medial portion 422 has a crosssectional area that is smaller than the cross sectional area of proximalportion 421 and smaller than the cross sectional area of distal portion423. Preferably medial portion 422 has a generally oblong cross-sectionwith a major axis M1 substantially equal to the internal diameter ofinlet 411. Alternatively, the major axis may be slightly greater thanthe internal diameter of inlet 411 to help ensure that septum 420remains in inlet 411. The minor axis M2 of medial portion 422 is smallerthan the diameter of proximal portion 421 and smaller than the internaldiameter of inlet 411. Thus, medial portion 422 has a cross-sectionalarea that is smaller than the cross-sectional area of inlet 411. Thisprovides a space between the external surfaces of medial portion 422along the major axis thereof and the sidewalls of housing 410 thatdefine inlet 411 where the material of septum 420 can be displaced whena male luer taper is disposed in septum 420. Enlarged distal portion 423defines an annular slot 426 extending about the bottom thereof. Inaddition, an enlarged diametrical portion 427 extends across the bottomof enlarged distal portion 423.

A slit 425 is formed in septum 420 and extends longitudinally throughproximal portion 421, medial portion 422 and distal portion 423. As seenin the top plan view of septum 420 of FIG. 22, slit 425 has a transverseaxis T and is defined by a pair of sides 425 a and a pair of ends 425 b.Preferably, a diametrical portion of an enlarged distal portion extendsfrom sides 425 a of slit 425 along an apex back to the bottom surface ofenlarged distal portion. Diametrical portion provides increased massadjacent to the bottom of slit 425 to help keep slit 425 closed againstfluid flow.

Septum 420 is disposed in top portion 412 of housing 410 such thatenlarged proximal portion 421 rests on top of top surface 415. As aresult, enlarged proximal portion 421 projects above the top of inlet411. In addition, because of the undulating configuration of top surface415, proximal portion 421 is pushed upon along high points A. Septum 420is aligned in housing 410 such that the middle of sides 425 a of slit425 are aligned with each of the high points and transverse axis T isaligned with the low points. Thus the minor axis of medial portion 422is aligned with the high points and the major axis of medial portion 422is aligned with the low points. Distal portion 423 is captured betweentop portion 412 and bottom portion 416 of housing 410 such thatpreferably the top wall of bottom portion 416 engages annular slot 26 ofseptum 420. The bottom wall of top portion 412 is bonded to acircumferential flange 419 formed along a medial portion of bottomportion 423 adjacent to luer lock collar 416 a. If desired, an annularslot 419 a can be formed in flange 419 and the bottom wall of topportion 412 can be inserted into annular slot 419 a. Any standardbonding technique, such as chemical adhesive or ultrasonic welding canbe used to bond top portion 412 to bottom portion 416. Preferably,medial portion 422 is held in tension when septum 420 is located inhousing 410. This tension in combination with portions of proximalportion 421 being lifted up by high points A on top surface 415 resultsin a compressive force being exerted against sides 425 a to force slit425 closed at least at the top of proximal portion 421.

When a male luer taper of another medical device, such as a syringe, ispushed against the top of proximal portion 421 of septum 420, proximalportion 421 deflects distally and laterally and allows the male luertaper to access slit 425 in septum 420. As the male luer taper is pushedfurther into slit 425, medial portion 422 also deflects distally andlaterally. By having a cross-section for medial portion 422 that issmaller than the cross-section of bore 413, space is provided insidebore 413 to allow such lateral deflection of medial portion 422. Thisdistal and lateral deflection of septum 420 forces slit 425 to open andallows the male luer taper to penetrate septum 420 into slit 425. Whenthe male luer taper is fully inserted into septum 420, slit 425 isforced open along the entire length of septum 420 and thus allows fluidto flow through septum 420 and the needleless luer access connector.Thereafter, the male luer taper of the other medical device can bewithdrawn from slit 425. The inherent resiliency of septum 420 causesseptum 420 to return to its normal unstressed state with slit 425closed. This prevents any further fluid flow through septum 420.

The catheter adapter may be selectively connected to a source ofanesthesia 300 via the extension tube. Such a fluid supply line can beconnected to extension tube 25 prior to insertion of assembly 10 into apatient. In such case, a stopcock or Roberts clamp is provided toprevent fluid flow through the extension tube until desired. Further, asyringe may be employed as an anesthesia source to engage the luer lockadapter 126, allowing the clinician to deliver controlled doses ofanesthesia using a syringe. Side port 22 is in fluid communication withthe lumen of catheter 21 via the opening 122 so that fluid infusedthrough extension tube 25 will pass into the patient once catheter 21 isproperly positioned in the patient.

Catheter adapter 24 may also include a pair of wings 26 that extendsradially 25 outwardly from either side of catheter adapter 24. Wings 26are preferably located adjacent to side port 22 below the main bodyportion of catheter adapter 24. Wings 26 facilitate manipulation ofcatheter assembly 20 and enhance patient comfort when catheter assembly20 is affixed to the patient. Wings 26 may include suture holes 28 tofacilitate fixation of catheter assembly 20 to the patient.Alternatively, various adhesive systems may be employed to affix thecatheter adapter to the patient's skin. The proximal end of catheteradapter 24 is sealed with a septum 29 to ensure that fluid does not leakout of the proximal end of catheter adapter 24. The septum can be asingle plug bonded to the catheter adapter. Alternatively, the septum 29may be formed from two portions, a proximal portion 29 a and a distalportion 29 b, each of which is pre-slit to facilitate locating anintroducer needle 31 there through.

Septum distal portion 29 b provides the primary seal preventing fluidflow past septum while septum proximal portion 29 a provides a secondaryseal. Although septum 29 could be formed from one piece, two pieces maybe used because it is easier and less expensive to manufacture. Inaddition, forming septum 29 from two separate pieces increases thecolumn strength and facilitates assembly into catheter adapter 1024.Preferably, septum distal portion 29 b and septum proximal portion 29 aare formed from the same material and have the same hardness. Suitablematerials for septum 29 include a peroxide-cured elastomer such aspolyisoprene, silicone and the like where the materials have a durometerin the range of 35-45 Shore A. Preferably, a septum housing 27 having anopen proximal end and an open distal end surrounds at least a portion ofseptum proximal portion 29 a and septum distal portion 29 b in aninterference fit to hold septum 29 in place in position in catheteradapter 24. Alternatively, septum 29 could be located in catheteradapter 24 without the use of housing 27. However, housing 27facilitates placement of septum 29 in catheter adapter 24.

As shown in the Figures, housing 27 extends only along the proximalportion of septum distal portion 29 b. However, if desired, housing 27could extend completely along the entire length of septum 29 or justalong septum distal portion 29 b. With such a configuration, it is to beunderstood that housing 27 would be configured so it would apply thedesired compressive force to septum 29 instead of catheter adapter 24 asdiscussed below. The open proximal and distal ends of housing 27 allowan introducer needle 31 to extend through septum 29 past housing 27.Preferably, the proximal end of housing 27 abuts and extends over aportion of the surface area of the proximal face of septum 29. Thisconfiguration prevents the attachment of another medical device to theproximal end of catheter adapter 24. Instead, any such medical devicethat should be connected to catheter adapter 24 would be connected tothe fluid access device 126 located at the proximal end of extensiontube 25.

Septum 29 and septum housing 27 are located in catheter adapter 24 sothat at least the distal portion of septum distal portion 29 b engagesthe inside of catheter adapter 24. The external diameter of at least thedistal portion of septum distal portion 29 b is greater than theinternal diameter of catheter adapter 24 at least along the portion thatengages the distal portion of septum distal portion 29 b. Preferably,the external diameter of the distal portion of septum distal portion 29b should be at least 5% larger than the internal diameter of therelevant portion of catheter adapter 24. With this configuration,catheter adapter 24 exerts a radial compressive force against distalportion 29 b. This compressive force helps to hold housing 27 in placeand also helps to seal septum distal portion 29 b after introducerneedle 31 has been withdrawn from septum 29 so that septum distalportion 29 b does not take a compression set about introducer needle 31.The portion of catheter adapter 24 that engages septum distal portion 29b should be arranged such that the proximal end of septum 29 is adjacentto the open proximal end of catheter adapter 24 when catheter adapter 24engages septum distal portion 28 b. Septum housing 27 and septum 29could also be affixed inside catheter adapter 24 using an alternatetechnique such as by an interference fit between housing 27 and catheteradapter 24, the use of an adhesive or by ultrasonic welding.

Septum 29 defines a cavity or hollow interior portion 29 c formedbetween septum proximal portion 29 a and septum distal portion 29 b.This minimizes drag on introducer needle 31 as it is being withdrawnfrom catheter assembly 20. Testing of septum 29 against a standardseptum shows that the average drag force for septum 29 with hollowinterior portion 29 c is about 0.15 pounds while the average drag forcefor a septum without a hollow interior is about 0.30 pounds. Hollowinterior portion 29 c should be sized to minimize drag but it must notbe too large so that it acts as a reservoir for microbial growth thereinif fluid were to become trapped therein. Hollow interior portion 29 ccould have a cylindrical configuration such as shown in FIG. 7. However,preferably hollow interior portion 29 c has a configuration such asshown in FIG. 11 where the proximal section is generally cylindrical,the medial section is tapered such that it increases in diameter in thedistal direction, and the distal section is tapered such that itdecreases in diameter in the distal direction. Preferably the tapershould be between about 2 degrees and about 10 degrees to the horizontalplane. This configuration reduces the volume of dead space that couldbecome a reservoir for blood when introducer needle 31 is withdrawn fromcatheter 21. Thus the cross section of hollow interior portion 29 cshould closely approximate the cross section of the largest needle thatwould be used for introducer needle 31. Preferably, hollow interiorportion 29 c is between about 6 and about 8 millimeters in length. Ifdesired, hollow interior portion 29 c could be filled with some materialto prevent unwanted material from becoming trapped therein. If alubricious material such as a silicone liquid or gel is disposed inhollow interior portion 29 c that material could also serve to enhancethe drag-reducing characteristic of septum 29.

In certain implementations of the invention, the septum 29 is longerthan the distance between the distal end of introducer needle 31 and theproximal end of notch 33. This prevents fluid or blood from leaking outof catheter assembly 20 when introducer needle 31 is being withdrawntherefrom. As shown in FIG. 8, during withdrawal of introducer needle31, when the distal end of introducer needle 31 is distal of septumdistal portion 29 b and notch 33 is located in hollow interior portion29 c anesthesia fluid can flow into introducer needle 31 and into hollowinterior portion 29 c but anesthesia fluid or blood cannot flow out ofcatheter assembly 20 because of the proximal portion of septum proximalportion 29 a. As shown in FIG. 9, during withdrawal of introducer needle31 when the distal end of introducer needle 31 is located in the distalportion of septum distal portion 29 b, there is no longer a fluid flowpath through introducer needle 31 and thus fluid cannot escape fromcatheter assembly 20. Finally, as shown in FIG. 10, continued withdrawalof introducer needle 31 allows the proximal portion of septum proximalportion 29 a to wipe introducer needle 31 of any residual fluid that maybe disposed thereon.

Alternatively, the proximal portion of septum proximal portion 29 a andthe distal portion of septum distal portion 29 b could each be at leastas long as the distance between the distal tip of introducer needle 31and the proximal end of notch 33 formed in the sidewall of introducerneedle 31. See FIGS. 4 and 5. This dimension ensures that no flow pathis created through introducer needle 31 between the proximal and distalsides of either septum distal portion 29 b or septum proximal portion 29a. This will thus minimize fluid leakage into hollow interior portion 29c as introducer needle 31 is removed from septum distal portion 29 b.

In order to minimize drag on introducer needle 31, the distal portion ofseptum distal portion 29 b and the proximal portion of septum proximalportion 29 a should not be longer than about 3 millimeters. Preferably,the distal portion of septum distal portion 29 b should be between about2 and about 3 millimeters long while the proximal portion of septumproximal portion 29 a should be between about 1 and about 2.5millimeters long. In addition, the septum 29 and/or septum housing 27can include needle capture and shield functionality, which couldeliminate the need for a separate needle shield 200 of the typediscussed above.

Introducer needle assembly 30 includes introducer needle 31 having asharp distal tip 32 defined by a bevel, a central bore 130 and aproximal end connected to a needle hub 34. The needle (excluding thevery tip) may be coated with a lubricant that is an electric insulator.Leads 140 may be connected to the needle at its proximal end to allowthe delivery of an electrical charge to the needle, as discussed below.The lead 140 may be, welded, crimped or soldered (or a combination ofthese) to the proximal end of the needle. Alternatively, the leads couldbe formed integrally with the needle itself, or with a collar in theneedle hub in which the needle sits. Further, the leads could beattached to a collar that is within the needle hub and that grips theneedle. Introducer needle 31 is preferably formed from stainless steeland has a longitudinal axis that is generally parallel to thelongitudinal axis of catheter and introducer needle assembly 10.Introducer needle 31 may be formed with notch 33, i.e., a hole oropening in the sidewall, adjacent to the distal end to allow fluid toflow into the open distal end of introducer needle 31, through thecentral bore, and then out of notch 33 into the annular space 171between catheter 21 and introducer needle 31. Alternatively, the notch33 may be positioned on the needle 31 such that it is aligned with orsubstantially aligned with opening 122 in the insertion position (seenotch 33′ as shown, for example, in FIG. 3). In such case, fluid passingthrough the tube 25 will flow directly through opening 122 into thenotch 33′, and out of the tip 32 of the needle 31. The tip of thecatheter is narrowed to sealingly engage the needle near the tip. Asdiscussed below, the seal will direct fluid flow in the annular spacethrough the notch, rather than out the distal end of the catheter.

A vented plug, which allows air but not fluid to flow there through, maybe provided at the fluid access device to permit blood flow into theextension tube 25. Needle hub 34 may be formed from the same types ofmaterials that are used to form catheter adapter 24. Of course, othermaterials could be used to form needle hub 34.

As will be understood, the instant invention permits the delivery ofperipheral block anesthesia via a “closed” system, that is, a systemthat does not create an open conduit from the environment to thepatient's tissue. Such systems are desirable because they can reducerisk of infection. In the implementation of the invention depicted inthe Figures, the needle is withdrawn through a septum 29 (thusmaintaining system closure), and the anesthesia is introduced throughthe luer lock adapter 126, which an also be a closed system device suchas that disclosed in U.S. Pat. No. 6,171,287 or that depicted in FIGS.18-22, referenced above.

To use the catheter and needle assembly 10, the clinician first insertsthe needle tip 32 into the patient's tissue. Typically, the clinicianwill use anatomical landmarks to determine where to insert the needle31. The clinician will also receive tactile feedback from the patient'stissue. For example, if the needle tip is moving adjacent to an artery,the clinician can feel the pulsing blood. Further, the clinician candetect parasthesia should the needle tip actually “hit” the nerve. Toassist in locating the needle tip, the clinician can provide anelectrical charge, via the leads 140, to the needle 31. Since thecatheter 21 is made of an electrical insulating material, the charge onthe needle 31 only passes to the patient's tissue at the needle tip.Consequently, the clinician can observe the response of the tissuesurrounding the tip, discerning the precise location of the tip withinthe target tissue.

After confirming placement of introducer needle 31 and catheter 21 inthe target tissue, the clinician can then attach a source of anesthesia300, such as a filled syringe, to the luer lock adapter 126 (this canalso be done before insertion of the catheter and introducer needleassembly, as desired by the particular clinician). As the clinicianactuates the syringe, anesthesia fluid passes through the extension tubeto the catheter adapter 24. When the notch 33 is positioned near the tip32 of the needle 31, the fluid passes through the annular space 171. Theseal formed between the tip of the catheter and the tip of the needledirects the fluid in the annular space through the notch 33 in theneedle 31 into the central bore of the needle 31 and out the open tip ofthe needle 31. When the notch 33′ (see FIG. 3) is alternativelypositioned in alignment with opening 122 of the adapted 21, theanesthesia fluid passes directly through the notch 33′, into the centralbore of the needle 31 and out the open tip 32 of the needle 31.Anesthesia is thus delivered through the extension tube to the catheteradapter 26 and out the needle tip 22. The clinician is therefore able toimmediately deliver anesthesia to a precise location in the patient'stissue.

After this initial introduction of anesthesia, the clinician thenwithdraws introducer needle 31 from catheter 21 by moving needle hub 34proximally while holding the catheter adapted 24 in place on thepatient. Introducer needle assembly is removed from catheter adapter 24and disposed of according to the facility's disposal protocol. Again,because of septum 29, blood and liquid anesthesia will not escape fromcatheter adapter 24 even as the needle is removed. A needle shield 200may be provided in the assembly. In such case, the tip of the needle 31will be shielded upon withdrawal as shown in FIG. 23. Further details ofthe needle shield 200 can be found in U.S. patent application Ser. Nos.09/590,600 and 09/717,148, and in WO 01/93940, referenced above.

As can be appreciated, during infusion of the anesthetic it is desirablethat a clinician be able to aspirate though the device to assure thatthe needle point 32 is not accidentally located within an artery (whichanatomically is very near the target nerves). The need to aspirate is sothat a clinician can determine if the device is in the venous systemprior to infusing significant amounts of anesthetic, which could resultin a very detrimental result if infused into the venous system. If thedevice accidentally penetrates an artery, during aspiration blood wouldbe drawn through the needle point 32, out through the notch 33 in theneedle 31, and visualized in the annular space between the needle 31 andthe catheter 21 and all fluid connection locations proximal of the notch33 (i.e. catheter adapter and extension tubing) if the notch 33 islocated near the distal end of the needle. If the notch 33′ is locatedin the catheter adapter 24 the aspirated blood would be visualized inthe clear/translucent catheter adapter 24 and points proximal of thenotch located within the catheter adapter 24.

The clinician can then bend wings 26 so they match the contour of thepatient's skin and suture catheter assembly 20 to the patient's skinusing suture holes 28. Alternatively, the clinician can tape catheterassembly 20 to the patient's skin, or use some other method ofaffixation. The catheter remains within the patient with the tip of thecatheter in the tissue to be anesthetized. The clinician can deliveradditional anesthesia to the tissue by delivering anesthesia to the luerlock adapter 126 as discussed above.

Another implementation of an aspect of the present invention is shown inFIGS. 14-18. Similar to introducer needle assembly 10 discussed above,the introducer needle assembly 300 comprises a needle assembly 302 and acatheter assembly 304. Needle assembly 302 includes a needle handle 306having an opening 307 that mates with a bayonet mounting pin 321 on thecatheter assembly 304. A needle 308 having a notch 310 and open needletip 311, and constructed similar to needle 31 discussed above, ismounted in the needle handle 306 by, for example, adhesive or any othersuitable mounting material or technique. Alternatively, the notch 310can be configured as notch 310′ shown in FIG. 18 to be positioned at amore proximal location along needle 308 to function in a manner similarto notch 33′ discussed above. The needle handle 306 has a rear openingwhich is capable of receiving an electrical connector assembly 314 thatcan removably attach to the back of the needle 308. The connector 314 iscoupled to a conduit 316 that is further coupled to another connector318 having an opening that enables the connector 318 to couple to aconnector of a power supply (not shown) to deliver current to the needle308 in a manner similar to that discussed above.

The needle 308 is received into the catheter assembly 304 which includesa catheter 322 into which the needle passes 308, so that an annularspace 323 similar to annular space 171 discussed above is formed betweenthe needle 308 and catheter 322. Catheter assembly 304 further includesa side port 330 having an opening 331 configured similar to opening 122discussed above. The side port 330 is connected to conduit 326 that isfurther connected to an adapter 324 having an opening 328 therein.Adapted 324 can include a closed-system access port, such as theneedleless luer access connector disclosed in U.S. Pat. No. 6,171,287referenced above and shown in FIGS. 19-22. Catheter assembly alsoincludes a septum 332 and septum housing 334 similar to septum 29 andseptum housing 27, respectively, as discussed above. Catheter assembly304 further includes bayonet mounting pin 321 that is received and mateswith opening 307 in needle handle 306 to removably secure needle handle306 to catheter assembly 304. Specifically, the bayonet pin 321 entersthe opening 307 and becomes snap fit with the catheter adapted 324 bytwisting the catheter adapter 324 and needle handle 306 relative to eachother about their respective axes, thus securing the catheter adapter324 to the needle handle 306 so that they do not separate as theclinician is searching for the nerve. That is, in the process of findingthe right nerve the clinician may withdraw the needle/catheter multipletimes which could cause the catheter adapter 324 to separate from theneedle handle 306 allowing the tip of the catheter 322 to extend beyondthe needle tip 311. The bayonet pin and slot arrangement secures the twotogether until the clinician disconnects the two by twisting the bayonetmounting pin 321 past a snap in the needle handle 306 allowing it tocome out the slot in the distal end of the handle 306.

The needle 308, catheter assembly 304, catheter 322 and relatedcomponents are made of materials similar to those discussed above. Theintroducer needle assembly 300 can thus be used to deliver anesthesia ina manner similar to introducer needle assembly 10 as discussed above.

Although the embodiments of the present invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims. For example, while certain aspects of the currentinvention are depicted in the context of a side ported catheter adapter,it will be appreciated that other ports of catheter adapters and hubsmay be employed in conjunction with aspects of the invention. Forexample, a closed system access port may be used to serve as the septum.The needle would then pass through the access port until removed. Onceremoved, a luer tip syringe can then access the access port.

1. A method for delivering anesthesia including: providing a needle witha notch, a tip and a central bore passing through the needle andcreating a fluid flow path between the notch and the tip, wherein theneedle is formed of a material capable of conducting an electricalcharge; providing a catheter having a proximal end and a distal enddisposed slidingly about the needle such that an annular space is formedbetween at least a portion of the needle and the catheter and the tip ofthe needle extends out of the distal end of the catheter; wherein theneedle and catheter form a catheter assembly; inserting the catheterassembly into tissue to be anesthetized; delivering an electrical chargeto the needle, whereby the tissue in contact with the tip receives thecharge; and delivering anesthesia into the annular space such thatanesthesia flows through the annular space, through the notch, throughthe central bore and out the tip of the needle.
 2. The method of claim 1further including: withdrawing the needle from the catheter; anddelivering additional anesthesia, at selected times, to the tissuethrough the catheter.
 3. The method of claim 2 wherein a catheter hub isprovided connected to the catheter, the method further includingaffixing the catheter hub to the patient.
 4. The method of claim 3wherein wings are attached to the catheter hub and the hub is attachedto the patient by taping at least the wings to the patient's skin. 5.The method of claim 3 wherein an extension tube is attached to the hub,and wherein anesthesia is delivered to the hub via the extension tube.6. The method of claim 1 wherein the catheter is translucent ortransparent.
 7. The method of claim 1 wherein the notch is disposed nearthe tip of the needle within the catheter.
 8. The method of claim 1wherein a catheter hub is provided attached to the catheter and whereinthe catheter hub has a side port such that a fluid path is formedbetween the side port and the catheter.
 9. The method of claim 8 whereinthe catheter forms a seal with the needle near the tip distal to thenotch.
 10. The method of claim 1 wherein the notch is disposed withinthe catheter adapter,
 11. The method of claim 1 wherein the needle,excluding its tip, is coated with a lubricant that is an electricalinsulator.
 12. A method for delivering anesthesia including: providing aneedle formed of a material capable of conducting an electrical charge;providing a catheter having a proximal end and a distal end slidinglydisposed about the needle such that the tip of the needle extends out ofthe distal end of the catheter; providing a closed system access influid communication with the catheter; wherein the needle and catheterform a catheter assembly; inserting the catheter assembly into tissue tobe anesthetized; delivering an electrical charge to the needle, wherebythe tissue in contact with the tip receives the charge delivering fluidto the catheter via the closed system access port.
 13. A method fordelivering anesthesia including: providing a needle with a notch, a tipand a central bore passing through the needle and operably connectingthe notch and the tip; providing a catheter having a proximal end and adistal end disposed slidingly about the needle such that an annularspace is formed between at least a portion of the needle and thecatheter and the tip of the needle extends out of the distal end of thecatheter; wherein the needle and catheter form a catheter assembly;inserting the catheter assembly into tissue to be anesthetized; anddelivering anesthesia into the annular space such that anesthesia flowsthrough the annular space, through the notch, through the central boreand out the tip of the needle.
 14. A method for delivering anesthesiaincluding: providing a needle with a notch, a tip and a central borepassing through the needle and creating a fluid flow path between thenotch and the tip, wherein the needle is formed of a material capable ofconducting an electrical charge; providing a catheter having a proximalend and a distal end disposed slidingly about the needle such that anannular space is formed between at least a portion of the needle and thecatheter and the tip of the needle extends out of the distal end of thecatheter and the notch is disposed within the catheter; wherein thecatheter electrically insulates the needle excluding the tip; whereinthe needle and catheter form a catheter assembly; inserting the catheterassembly into tissue to be anesthetized; delivering an electrical chargeto the needle, whereby the peripheral nerve tissue near the tip receivesthe charge, thereby exciting the enervated tissue, causing a responseand thereby identifying the location of the nerve; and deliveringanesthesia into the annular space such that anesthesia flows through theannular space, through the notch, through the central bore and out thetip of the needle.